1. Field of the Invention
The present invention relates to data input apparatuses used, for example, for handling three-dimensional figures in computer graphics.
2. Description of the Related Art
In image processing on a workstation or a personal computer, a three-dimensional structural formula of a molecule can be displayed on a computer screen for research and development, or a three-dimensional figure can be displayed on the screen in game simulation or architectural simulation. As it is necessary to move or rotate the three-dimensional structural formula or the three-dimensional figure on the screen, a controller for manipulating such a three-dimensional figure in a three-dimensional manner on the screen is required.
As such a controller, a keyboard is conventionally used by pressing an assigned key to change the mode to a three-dimensional mode.
Japanese Unexamined Patent Publication Nos. 2-282818 and 5-233146 have disclosed three-dimensional-figure controllers used in computer graphics.
Japanese Unexamined Patent Publication No. 5-233146 describes a three-dimensional-figure controller 10 shown in FIG. 6. The controller 10 is provided with a truncated-cone-shaped, large-diameter ring 12 disposed rotatably, a spherical trackball 11 disposed rotatably in two directions perpendicular to each other and the diagonal directions, at the center of the ring 12, and a ring-shaped upper cover 13 disposed at an upper portion of the trackball 11.
In the controller 10, the trackball 11 generates a two-dimensional-figure signal and the added rotatable ring 12 allows a three-dimensional-figure signal to be produced.
An internal structure of the controller 10 will be described below with reference to FIG. 7. The trackball 11 disposed in the controller 10 is butted against rollers 14 disposed below the trackball, the rollers 14 being supported by shafts disposed in two directions perpendicular to each other. A small roller 17 is also disposed in the vicinity of the rollers 14 to prevent the trackball 11 from dropping. At one end of each roller 14, a circular plate 15 having slits at its periphery is formed so as to rotate together with the roller 14. At a part of the periphery of each circular plate 15, an encoder 16 such as an optocoupler is provided for detecting the direction and the amount of rotation of the trackball 11. The large-diameter ring 12 is also provided with slits (not shown) at a side face formed at the periphery. An encoder is disposed to detect the direction and the amount of rotation of the ring 12.
The data detected by the encoders 16 and the other encoder is converted to a coordinate on a display screen to allow the object shown on the screen to move and rotate three-dimensionally in real time.
Usually in the controller 10, the trackball 11 is operated with the forefinger, the middle finger, or the third finger, and the ring 12 is operated with the thumb.
The controller has the following drawbacks.
(1) When two-dimensional coordinate data in the X-Y plane is input with the trackball 11, it is necessary to switch the mode by operating a switch such as an assigned key on the keyboard to enable either a movement-data input mode, in which the object indicated by the cursor or the image on the screen is simply moved in the plane, or a rotational-data input mode, in which the object is rotated about the X axis or the Y axis. This operation is troublesome. PA0 (2) It is necessary to press an assigned key on the keyboard to change the mode to the three-dimensional-figure input mode and a key operation is also required to return to the two-dimensional input mode. Such operations are troublesome and reduce operation efficiency. PA0 (3) To increase operability in the controller 10 shown in FIG. 6, it is necessary to extend the diameter of the trackball 11. When the diameter is extended, the depth and width are accordingly increased and the diameter of the ring 12, which is formed around the trackball 11, is also increased. Therefore, the controller 10 becomes a thick structure. In addition, since this means it is difficult to design a compact controller, the controller is provided with difficulty for a compact computer such as a notebook-type computer. Operation is troublesome in some cases since it is necessary to use many fingers and the range in which a finger moves needs to be extended in relation to the trackball 11 and the ring 12.